Hyperglycemia In Normal Rats Research Articles

Artemisia absinthium L. Aqueous and Ethyl Acetate Extracts: Antioxidant Effect and Potential Activity In Vitro and In Vivo against Pancreatic α-Amylase and Intestinal α-Glucosidase.

Artemisia absinthium L. is one of the plants which has been used in folk medicine for many diseases over many centuries. This study aims to analyze the chemical composition of the Artemisia absinthium ethyl acetate and its aqueous extracts and to evaluate their effect on the pancreatic α-amylase enzyme and the intestinal α-glucosidase enzyme. In this study, the total contents of phenolic compounds, flavonoids, and condensed tannins in ethyl acetate and the aqueous extracts of Artemisia absinthium leaves were determined by using spectrophotometric techniques, then the antioxidant capacity of these extracts was examined using three methods, namely, the DPPH (2, 2-diphenyl-1picrylhydrazyl) free radical scavenging method, the iron reduction method FRAP, and the β-carotene bleaching method. The determination of the chemical composition of the extracts was carried out using high-performance liquid chromatography—the photodiode array detector (HPLC-DAD). These extracts were also evaluated for their ability to inhibit the activity of the pancreatic α-amylase enzyme, as well as the intestinal α-glucosidase enzyme, in vitro and in vivo, thus causing the reduction of blood glucose. The results of this study showed that high polyphenol and flavonoid contents were obtained in ethyl acetate extract with values of 60.34 ± 0.43 mg GAE/g and 25.842 ± 0.241 mg QE/g, respectively, compared to the aqueous extract. The results indicated that the aqueous extract had a higher condensed tannin content (3.070 ± 0.022 mg EC/g) than the ethyl acetate extract (0.987 ± 0.078 mg EC/g). Ethyl acetate extract showed good DPPH radical scavenging and iron reduction FRAP activity, with an IC50 of 0.167 ± 0.004 mg/mL and 0.923 ± 0.0283 mg/mL, respectively. The β-carotene test indicated that the aqueous and ethyl acetate extracts were able to delay the decoloration of β-carotene with an inhibition of 48.7% and 48.3%, respectively, which may mean that the extracts have antioxidant activity. HPLC analysis revealed the presence of naringenin and caffeic acid as major products in AQE and EAE, respectively. Indeed, this study showed that the aqueous and ethyl acetate extracts significantly inhibited the pancreatic α-amylase and intestinal α-glucosidase, in vitro. To confirm this result, the inhibitory effect of these plant extracts on the enzymes has been evaluated in vivo. Oral intake of the aqueous extract significantly attenuated starch- and sucrose-induced hyperglycemia in normal rats, and evidently, in STZ-diabetic rats as well. The ethyl acetate extract had no inhibitory activity against the intestinal α-glucosidase enzyme in vivo. The antioxidant and the enzyme inhibitory effects may be related to the presence of naringenin and caffeic acid or their synergistic effect with the other compounds in the extracts.

GC\u2013MS analysis, toxicological and oral glucose tolerance assessments of methanolic leaf extract of Eucalyptus globulus

BackgroundEucalyptus globulus leaf has shown promising potential in its efficacy to manage some diseases but little is known about its safety and its use in the management of diabetes. This study was designed to identify the bioactive compounds present in Eucalyptus globulus leaf extract (EGLEX), assess its toxic effects and its oral glucose tolerance ability. Powdered Eucalyptus globulus leaf was extracted with methanol using standard extraction procedure. Preliminary phytochemistry, gas chromatography–mass spectrometry (GCMS) analysis of the extract, its acute and subacute toxic effects and on its glucose tolerance (in-vivo) capability were assessed using standard laboratory techniques.ResultsEGLEX was tested positive for the presence of alkaloids, cardiac glycosides, flavonoids, tannins, phlobatannins and terpenoids. Nine compounds were identified by GCMS analysis of the leaf extract. EGLEX (up to 300 mg/kg bwt) showed no toxicity in all the rats dosed for the period of 14 days. The histomorphological study of the liver and kidney tissues harvested from rats dosed with 2000 mg/kg bwt showed features of histoarchitectural distortions in the two tissues. EGLEX (200 mg/kg bwt) further demonstrated effective glucose utilization as insulin and metformin.ConclusionsThe results obtained deduced that EGLEX is safe at a lower dose of 300 mg/kg bwt but toxic at higher dose of 2000 mg/kg bwt, and that single dose (200 mg/kg bwt) of the plant extract prevented hyperglycemia in normal rats.

Physiochemical, Insecticidal, and Antidiabetic Activities of Senna occidentalis Linn Root.

The present study aimed to investigate the physiochemical activities of Senna occidentalis (Linn) roots and phytochemicals as insecticidal (ethyl acetate and methanol) and antidiabetic (ethanolic extract) activities. Physicochemical properties were carried out by using Association of Official Analytical Chemist methods; thin layer chromatography was carried out according to the Stahl method. Larvicidal activity and LD50 were studied against the third instar of Culex quinquefasciatus mosquito larvae to detect and extract toxicity. The ethanolic extracts of the roots were orally tested at the dose 200 mg/kg for the hypoglycemic effect on induced hyperglycemia in normal rats, assessed in the ethanol extract, and were compared with diabetic control and standards glibenclamide 10 mg/kg. Physiochemical parameters showed high rate in the nitrogen-free extract (69.6%), curd fiber (14.5%), crude proteins (8.15%), ether extract (3.75%), and both ash and moisture (2%), and high concentrations values were found in potassium (43 mg/l) followed by phosphorous (28.5 mg/l), calcium (15 mg/l), sodium (3.65 mg/l), and magnesium (0.145 mg/l). In this part, phytochemical compounds showed high amount of alkaloids, triterpene, flavonoids, tannins, sugars, and few amount of anthraquinone glycosides. Thin-layer chromatography (TLC) studies different colored phytochemical constituted with different Rf values. All the spots are colored under UV light, but some are localized colorless after spaying. The ethyl acetate (EtAc) extract showed eight spots, and the methanol (MeOH) extract showed thirteen spots. The larvicidal activity showed that the ethyl acetate extract was safe against mosquito larvae with an LD50 value 1412.54 (p < 0.05), and the methanol extract had moderate larvicidal activity against mosquito larvae with an LD50 value 257.54 (p < 0.05), while the ethanolic extract of Senna occidentalis (L.) causes a favorable hypoglycemic activity when compared to control significant reduction by [53.15%, 32.87%, and 20.94%], respectively, as well as standard glibenclamide. Based on the various data of the physicochemical parameters, TLC spots, and phytochemical compounds of Senna occidentalis root, they could be used as references standards for manufacturing units of Senna occidentalis root larvicidal and antidiabetic drugs.

Pharmacological Modeling and Study for Antidiabetic Activity of Praecitrullus fistulosus Leaves Extracts

Phytochemical and pharmacological investigations of leaves of Praecitrullus fistulosus for the antidiabetic activity have been done in our research work encompassed in depth and systematic screening of plant leaves and further extraction, characterization and bioevaluation. The research was envisaged for antidiabetic activity of different extracts procured by successive extraction methods and to find out or isolate the most possible active compounds from the active extracts showing the best activity. The antidiabetic activity of all extracts has been evaluated by STZ induced diabetes. The isolated compounds have been evaluated by in-vitro and in-vivo models. The alcohol soluble extractives values were found to be higher than water soluble extractive value. Alcohol being a moderately non polar solvent, able to extract polar and non-polar components yields higher extractive value. The ethanol extract shows significant enhancement in glucose tolerance in glucose fed hyperglycemic normal rats and produced a marked decrease in blood glucose levels at 200 mg/kg and 400 mg/kg body weight in streptozotocin-diabetic rats after 21 days treatment.&#x0D; Keywords: Praecitrullus fistulosus, Streptozotocin and Glibenclamide, diabetes, Pharmacological Evaluation

Oxidised palm oil and sucrose induced hyperglycemia in normal rats: effects of Sclerocarya birrea stem barks aqueous extract.

BackgroundConsumption of foods rich in carbohydrates and fats, result in an increase in obesity and consequently type 2 diabetes. The present study was carried out to evaluate the effects of oxidised palm oil and sucrose (SOPO +S) on some metabolic parameters and to investigate the effects of aqueous extract from barks of Sclerocarrya birrea on SOPO + S induced damages.MethodsDuring 16 weeks, animals received every day a supplement of oxidised palm oil (10 %) and 10 % sucrose as drinking water). Control rat received standard diet and drinking water without sucrose. At the end of this period, animal presenting intolerance in glucose test and insensitivity to insulin were continuously feed with hypercaloric diet along with the administration of the plant extract (150 or 300 mg/kg) or glibenclamide (10 mg/kg) during three weeks. OGTT was performed; insulin sensitivity was assessed by performing insulin tolerance test and determining insulin sensitivity index (Kitt). Several parameters were evaluated including body weight, abdominal fat mass, blood glucose levels, blood pressure, serum lipid profile, and serum transaminases (ALT and AST). Oxidative parameters were measured by MDA levels, nitrites levels, SOD levels, reduced glutathione content and by enzyme activities of SOD and catalase.ResultsAnimal receiving a supplement of oxidised palm oil and sucrose showed hyperglycaemia, glucose intolerance, insulin resistance and a significant increase in body weight and abdominal fat mass compared to normal rats. In addition, there was a significant increase of SOD in aorta and heart, nitrites in liver and kidney, malondialdehyde (MDA) in heart, liver and kidney. It was also observed a significant reduction in the activities of the SOD and catalase in liver, kidney and reduced glutathione levels in heart. Concomitant treatment of plant extract with SOPO + S brought glycaemia and blood pressure towards normal value, restored glucose tolerance and insulin sensitivity. The plant extract prevent the increase or decrease in the activity of the enzyme depending to the organ, reduced MDA and nitrites levels.ConclusionThese results highlighted the hyperglycaemic and oxidant character of SOPO + S diet and confirm the hypoglycaemic, and antioxidant action of sclerocarya birrea aqueous extract in diabetes.

Anti-hyperglycemic action of apigenin-6-C-β-fucopyranoside from Averrhoa carambola

A stimulatory effect of apigenin-6-C-β-fucopyranoside (1) on glucose uptake was observed when rat soleus muscle was incubated with 1, 10 and 100μM of this flavonoid glycoside. The presence of specific insulin signaling inhibitors, such as wortmannin, an inhibitor of phosphoinositide 3-kinase (PI3K), RO318220, an inhibitor of protein kinase C (PKC), PD98059, an inhibitor of mitogen-activated protein kinase (MEK), and HNMPA(AM)3, an insulin receptor tyrosine kinase activity inhibitor showed that apigenin-6-C-β-fucopyranoside triggers different metabolic pathways in skeletal muscle. The oral administration of crude extract, fractions and isolated flavonoids (apigenin-6-C-β-fucopyranoside (1) and apigenin-6-C-(2″-O-α-rhamnopyranosyl)-β-fucopyranoside (2)) from Averrhoa carambola leaves exhibited a potential hypoglycemic activity in hyperglycemic normal rats. Additionally, both flavonoids significantly increased the muscle and liver glycogen content after an acute treatment. The results indicate that A. carambola can be regarded as a potent antihyperglycemic agent with insulin secretagogue and insulin mimetic properties.

Synthesis and pharmacological evaluation of some novel 2-pyrazolines bearing benzenesulfonamide as anti-inflammatory and blood glucose lowering agents

A series of novel pyrazolines (2a–l) bearing benzenesulfonamide moiety were synthesized by condensing appropriate chalcone (1a–l) with 4-hydrazinobenzenesulfonamide hydrochloride. Structure of all novel synthesized compounds was characterized on basis of elemental analysis data and spectral data (IR, 1HNMR, MS). Compounds (2a–l) were screened for in vivo anti-inflammatory action in carrageenan-induced rat paw edema model and blood glucose lowering action in glucose fed hyperglycemic normal rats. Compounds 2a, 2e, and 2l showed significant anti-inflammatory action (more than 75 %) at 5 h and also showed superior gastrointestinal safety profiles as compared to celecoxib. One compound (2i) was found to exhibit significant blood glucose lowering activity.

Synthesis and blood glucose lowering activity of some novel benzenesulfonylurea derivatives substituted with 6-aryl-4,5-dihyropyridazin-3(2H)-ones

Five (2a–e) benzenesulfonylurea derivatives bearing pyridazinone were synthesized by refluxing the appropriate 6-aryl-2-(p-sulfamylphenyl)-4,5-dihydropyridazine-3(2H)-one with benzylisocyanate in dry acetone over anhydrous K2CO3. These compounds were characterized by elemental analysis and various spectroscopic techniques viz; IR, 1H NMR, 13C NMR, and MS data. These compounds (2a–e) at the dose of 20 mg/kg were tested for blood glucose lowering activity in glucose-fed hyperglycemic normal rats. Compound 2b showed more potent anti-hyperglycemic activity than the standard drug gliclazide. The compound 2b was also tested for its hypoglycemic effect in fasted normal rats. It also showed significant hypoglycemic effect (but less than that of gliclazide).

Synthesis and blood glucose lowering activity of some novel benzenesulfonylthiourea derivatives substituted with 6-aryl-4,5-dihyropyridazin-3(2H)-ones

Some new benzenesulfonylthiourea derivatives substituted with pyridazinone (2a–o) were synthesized by refluxing the appropriate 6-aryl-2-(p-sulfamylphenyl)-4,5-dihydropyridazine-3(2H)-ones with isothiocyanate in dry acetone over anhydrous K2CO3. All the synthesized compounds were characterized on the basis of IR, 1H NMR, 13C NMR, DEPT and MS data, and elemental analysis. These compounds at the dose of 20 mg/kg were tested for blood glucose lowering activity in glucose-fed hyperglycemic normal rats. Five compounds (2a, 2d, 2l, 2m, and 2n) markedly reduced the content of glucose in rat blood (by more than 25%). Compound 2d showed the maximum reduction (38.8%).

Gatifloxacin-induced histamine release and hyperglycemia in rats

Gatifloxacin, a fluoroquinolone antimicrobial agent, has been reported to cause both hypoglycemia and hyperglycemia in diabetic and non-diabetic patients. The purpose of the present study was to investigate the mechanism of gatifloxacin-induced hyperglycemia in normal and diabetic rats. Rats received a single intravenous injection of gatifloxacin and samples of their arterial blood were collected periodically. Diabetic rats were produced by the injection of streptozotocin and nicotinamide. In normal rats, the concentration of serum glucose decreased after the injection of gatifloxacin at 50 mg/kg, while it increased with gatifloxacin at 100 mg/kg. The concentrations of serum epinephrine and histamine increased after the injection of gatifloxacin at 100 mg/kg. The increases in serum glucose and epinephrine concentrations were reduced by pretreatment with diphenhydramine at 1 mg/kg. In diabetic rats, the concentration of serum glucose actually increased after the injection of gatifloxacin at 50 mg/kg, concomitant with increases in the serum epinephrine and histamine concentrations. The concentration of serum immunoreactive insulin slightly increased after the injection of gatifloxacin at 50 mg/kg. In addition, repeated oral administration of gatifloxacin to rats at 300 mg/kg twice a day for 7 days did not change glucose tolerance. In conclusion, gatifloxacin-induced release of histamine can contribute to an increase in the serum epinephrine concentration and hyperglycemia in normal rats. In diabetic rats, lower doses of gatifloxacin can induce hyperglycemia owing to the low level of insulin secretion that they exhibit compared with normal animals.

Hypoglycemic and hypolipidemic effect of leaves from Syzygium cumini (L.) Skeels, Myrtaceae. in diabetic rats

Ethanolic crude extract (ECE) of leaves from Syzygium cumini (L.) Skeels, Myrtaceae was screened for its hypoglycemic and hypolipidemic activity (125, 250 and 500 mg/kg v.o.). Rats were divided into three groups for the evaluation of the hypoglycemic effect: normal rats, rats with alloxan-induced diabetes and hyperglycemic normal rats. Hypolipidemia was evaluated in rats with alloxan-induced diabetes. The antihyperglycemic activity was compared to treatment with glibenclamide, an oral hypoglycemic agent. The acute treatment with S. cumini ECE caused a significant decrease in the blood glucose in hyperglycemic normal rats (250 mg/kg), and in glucose (125 and 250 mg/kg), triglyceride (125 and 500 mg/kg) and cholesterol (125 mg/kg) levels of diabetic rats, but no effect was observed in the normal treated rats. Syzygium cumini leaves are a good candidate for alternative and/or complementary medicine in the management of diabetes mellitus, since they showed hypoglycemic activity in addition to a hypolipidemic action in diabetic animals.

Hyperglycemia induced by tacrolimus and sirolimus is reversible in normal sprague–dawley rats

Post-transplant diabetes mellitus (PTDM) worsens outcomes after kidney transplantation, and immunosuppression agents contribute to PTDM. We have previously shown that tacrolimus (TAC) and sirolimus (SIR) cause hyperglycemia in normal rats. While there is little data on the mechanism for immunosuppressant-induced hyperglycemia, we hypothesized that the TAC and SIR-induced changes are reversible. To study this possibility, we compared normal rats treated for 2weeks with either TAC, SIR, or a combination of TAC and SIR prior to evaluating their response to glucose challenge, with parallel groups also treated for 2weeks after which treatment was stopped for 4weeks, prior to studying their response to glucose challenge. Mean daily glucose and growth velocity was decreased in SIR, and TAC+SIR-treated animals compared to controls (P<0.05). TAC, SIR, and TAC+SIR treatment also resulted in increased glucose response to glucose challenge, compared to controls (P<0.05). SIR-treated animals also had elevated insulin concentrations in response to glucose challenge, compared to controls (P<0.05). Insulin content was decreased in TAC and TAC+SIR, and islet apoptosis was also increased after TAC+SIR treatment (P<0.05). Four weeks after treatments were stopped, all differences resolved between groups. In conclusion, TAC, SIR, and the combination of TAC+SIR-induced changes in glucose and insulin responses to glucose challenge that were accompanied by changes in islet apoptosis and insulin content. These changes were no longer present 4weeks after cessation of therapy suggesting immunosuppressant-induced changes in glucose metabolism are likely reversible.

Antihyperglycemic activity of naphthylchalcones

The purpose of the present work was to investigate, following previous works, naphthylchalcones as antihyperglycemic agent in glucose loaded animal model, insulin secretion as well as the action of these compounds on glucose uptake in a target tissue of insulin. The naphthylchalcones were found to have an acute serum glucose-lowering effect in hyperglycemic normal rats. In addition, chalcones 2 and 4 stimulated significantly the insulin secretion induced by glucose. These results suggest that the presence of nitro group and their position in the phenyl rings are responsible for the antihyperglycemic activity of chalcones. Additionally, the effect of chalcones on serum glucose-lowering seems to be a consequence of insulin secretion and these chalcones represent potential compounds with strong antihyperglycemic properties.

Nitrochalcones: Potential in vivo insulin secretagogues

In this study, the in vivo and in vitro anti-hyperglycemic activity of chalcone derivatives of 3,4-methylenedioxy, with a substituent electron-acceptor nitro group in the A or B ring, was investigated. As expected, the second generation sulfonylurea glipizide stimulated insulin secretion and reduced glycemia over the study period. Also, it was demonstrated for the first time that chalcones are able to increase insulin secretion and this event was coincident with serum glucose-lowering in the oral glucose tolerance test. Additionally, the chalcones studied had a similar effect on insulin secretion and serum glucose-lowering as glipizide. The effect of chalcones in terms of inducing insulin secretion was greater than that of glipizide after 30 min. Moreover, chalcones were not able to stimulate glucose uptake in soleus muscle, either in the presence of insulin or in the absence of this hormone. In addition, the oral treatment with chalcones did not alter glycemia in diabetic rats. These reports indicate that the effect of chalcones on serum glucose-lowering in hyperglycemic-normal rats is mainly a consequence of insulin secretion, highlighting these chalcones as novel compounds with strong anti-hyperglycemic properties.

Antihyperglycaemic activity of Sinularia firma and Sinularia erecta in streptozotocin-induced diabetic rats

The present study describes antihyperglycaemic activity in the two soft corals Sinularia firma Tixier Durivault and Sinularia erecta Tixier Durivault (phylum: Coelentrata). The methanolic extracts of S. firma and S. erecta exert a blood-glucose-lowering effect of 14.5% and 16.1%, respectively, on streptozotocin (STZ)-induced diabetic rats at an oral dose of 250 mg/kg body weight. These extracts were also found to inhibit the postprandial increase in hyperglycemia in normal rats by 13.0% and 12.7%, respectively, post sucrose challenge. Many compounds were isolated from these extracts; however none of them have shown a promising inhibitory effect on the tested enzymes of the insulin/glucose/glycogen cascade, i.e., protein tyrosine phosphatase-1B, glucose-6-phosphatase, and glycogen phosphorylase, respectively.

Acute effect of Trema micrantha (Ulmaceae) on serum glucose levels in normal and diabetic rats

Trema micrantha (Ulmaceae) ethanolic crude extract (ECE) was screened for its hypoglycemic activity (250, 500 and 1000 mg/kg v.o.).The animals were divided in three groups for the evaluation of the hypoglycemic effect: normal rats, rats with alloxan-induced diabetes and hyperglycemic normal rats. The antihyperglycemic activity was compared to the treatment with glibenclamide, an oral hypoglycemic agent. Serum glucose was analyzed after the treatment of the animals. The acute treatment with Trema micrantha ECE (250 and 1000 mg/kg) caused a significant decrease in the blood glucose levels in diabetic rats, but no effect was observed among the normal treated rats nor the hyperglycemic normal rats. Trema micrantha's leaves are a good candidate for alternative and/or complementary medicine in the management of diabetes mellitus, since they showed beneficial effects on blood glucose levels.

Effect of crude extract and fractions from Vitex megapotamica leaves on hyperglycemia in alloxan-diabetic rats

The effect of the crude extract, ethyl acetate and n-butanol fractions from Vitex megapotamica (Spreng) Moldenke on glycemia was investigated in diabetic rats. Oral administration of crude extract significantly reduced serum glucose levels in both normal and diabetic animals. In normal rats, serum glucose lowering was observed with 400 and 800 mg/kg at 2 and 2–3 h, respectively after oral crude extract treatment. Nevertheless, the hypoglycemic effect of Vitex megapotamica in diabetic rats was evident at 1 and 2 h and from 1 to 3 h after treatment with 400 and 800 mg/kg, respectively. The ethyl acetate as well as n-butanol fractions were able to diminish glycemia in diabetic animals. The ethyl acetate fraction (400 and 800 mg/kg) produced the maximum hypoglycemic effect (28 and 20%, respectively) in diabetic rats and the same dose of the n-butanol fraction reduced the hyperglycemia only by 11% at 1 h after treatment. Additionally, in hyperglycemic normal rats neither crude extract nor ethyl acetate fraction modified the glucose tolerance and the known tolbutamide effect on insulin release was clearly observed in this group. Thus, this study shows that Vitex megapotamica has an anti-hyperglycemic action, is able to ameliorate the diabetic state and, probably, is a source of hypoglycemic compounds.

Synthesis and antihyperglycemic activity profiles of novel thiazolidinedione derivatives

A number of thiazolidine-2,4-diones derivatives having carboxylic ester appendage at N-3 were synthesized and their antihyperglycemic activity was evaluated. Many of these derivatives as well as their corresponding carboxylic acid showed significant improvement on post-prandial hyperglycemia in normal rats, in contrast to their poor agonist activity at PPARγ.

Hypoglycemic effect and antioxidant potential of kaempferol-3,7-O-(alpha)-dirhamnoside from Bauhinia forficata leaves.

In vivo and in vitro treatments were carried out to investigate the effects of kaempferol-3,7-O-(alpha)-dirhamnoside (kaempferitrin), a major flavonoid compound of the n-butanol fraction from Bauhiniaforficata leaves, on serum glucose levels, as well as its antioxidant potential. Oral administration of kaempferitrin led to a significant hypoglycemic effect in normal and in alloxan-induced diabetic rats. In normal rats, blood glucose lowering was observed only with the higher dose of kaempferitrin (200 mg/kg) at 1 h after treatment. However, the hypoglycemic effect of kaempferitrin in diabetic rats was evident at all doses tested (50, 100, and 200 mg/kg), and this profile was maintained throughout the period studied for both higher doses. Additionally, in glucose-fed hyperglycemic normal rats, the kaempferitrin failed to decrease blood glucose levels. In vitro antioxidant properties or action against reactive oxygen species of this compound was also evaluated. The compound showed high reactivity with 1,1-diphenyl-2-picryl hydrazyl (DPPH), IC(50) of 84.0 +/- 7.8 microM, inhibited myeloperoxidase activity with K(0.5) = 86 +/- 9.9 microM, and decreased lipid peroxidation, induced by ascorbyl radical either in microsomes or in asolectin and phosphatidylcholine liposomes, with IC(50)'s of 320 +/- 14.1, 223 +/- 8.3, and 112 +/- 8.8 microM, respectively.

Inhibitory effects of mulberry leaf extract on postprandial hyperglycemia in normal rats.

We examined the inhibitory effects of aqueous ethanol extract from mulberry leaves (ME) on postprandial hyperglycemia in normal Wistar rats. ME dose-dependently suppressed the postprandial rise of blood glucose in rats, when ME (0.02-0.5 g/kg) was given 0.5 h before the administration of carbohydrates such as sucrose, maltose and starch. The ME dose showing 50% inhibition of the increment of blood glucose (ED50) was 0.11 g/kg for sucrose, 0.44 g/kg for maltose, and 0.38 g/kg for starch. ME and its basic fraction (MB) containing 1-deoxynojirimycin were assayed for their inhibitory effects (IC50) on disaccharidase derived from the small intestine of rats. The IC50 value of ME was 3.2 microg/mL for sucrase, 10 microg/mL for isomaltase, and 51 microg/mL for maltase. The IC50 value of MB was 0.36 microg/mL for sucrase, 1.1 microg/mL for isomaltase, and 6.2 microg/mL for maltase. The IC50 value of 1-deoxynojirimycin as the principle component in ME was 0.015 microg/mL for sucrase and 0.21 microg/mL for maltase, and this value was comparable to the IC50 of voglibose. The inhibitory activity of ME in a-amylase was weak. These results suggest that ME strongly suppresses postprandial hyperglycemia after carbohydrate loading by inhibiting the activity of disaccharidases in the small intestine of rats.